Earlier, another x37b launched into orbit for a 270-day "mission" last spring and landed at Vandenberg Air Force Base in California in December. This x37b, also known as an "Orbital Test Vehicle" or OTV, was scheduled to launch on Friday, but high-level ground winds during the first launch window, and clouds and heavy rain during the second launch window, forced a scrub of the launch for Friday. The launch took place from Cape Canaveral.
Resembling the space shuttle in its plane like shape, the x37b began initially as a NASA project in 1999. However, in 2004 it was transferred to the U.S. Department of Defense in 2004. Its first flight was a drop test from a "mother ship" on 7 April 2006, at Edwards Air Force Base. The space plane's first orbital mission, USA-212 was, as mentioned earlier, in 2010. It launched on April 22, 2010 using an Atlas V rocket. It returned to Earth on December 3, 2010. That was actually the first test of the OTV's heat shield and hypersonic aerodynamic handling.
In April of 2010, when the x37b launched into space for the first time, the China Daily newspaper wrote that the program raised concerns about an arms race in space. In fact, the extreme secrecy around the program has many in the U.S. wondering exactly what the DOD's plans for the x37b are.
Former Air Force officer and space security expert Brian Weeden said: "It's a mystery, because the Air Force is being so closed-mouthed about the program. It leads people to say, 'What exactly are they hiding?"
The x37b is 29 feet long, with a 15-foot wingspan. It is solar-powered when in space and is designed for orbital missions as long as 270 days.
The Atlas V rocket, which is used to propel the x37b into orbit, uses a Russian-built RD-180 engine burning kerosene and liquid oxygen to power its first stage. The upper stage, called the Centaur stage, uses an American-built RL10 engine burning liquid hydrogen and liquid oxygen.